1. Field of the Invention
The present invention relates to solution preparation and, more particularly, to brewing apparatus.
2. Description of the Prior Art
Infusers, which are used to make or brew a single serving of a beverage, for example, coffee, are well known. Generally, an infuser is used to bring a liquid into contact with a solid, usually in particulate form, to produce a potable liquid. The greater the area of the solid that is brought into contact with the liquid, the more quickly the infusion can be made. Also, the infusion can be achieved more quickly if liquid flow is maintained through the solid to repeatedly introduce liquid of lower solid concentration to the solid.
Known infusers work in a variety of ways. Some infusers employ gravitational forces, such as coffee makers in which hot water is poured through ground coffee beans held in a filter device. Some known infusers, such as electric percolators, utilize thermally produced pressure to either force the liquid through a basket holding the ground coffee beans or to draw the liquid through the basket by means of a vacuum created by the thermal forces. Other infusers, such as tea bags and tea balls, utilize turbulence and diffusion forces created by stirring, dunking, or steeping. Infusers are also known that include mechanical apparatus by which hydraulic pressure forces are created within a container. Finally, infusers are known that generate hydrostatic pressure to force liquid through an infusing substance, such as coffee.
Known infusers cannot effectively or practically be used with substances, such as coffee, that are difficult to infuse to produce a single serving. Infusers that include special apparatus for manually forcing the liquid through the solid are not commercially practical as single-serving coffee infusers. Single-serving infusers that are relatively simple in construction, such as bags and other types of liquid permeable containers, cannot develop adequate liquid flow to infuse coffee in a reasonable period of time. Many known infusers also permit the particulate solid to compact, thereby preventing an adequate area of the solid from making contact with the liquid. Such compaction is fatal when infusion of a single serving of coffee is attempted. A good discussion of the compaction problem may be found in U.S. Pat. No. 4,229,481 (hereinafter referred to as the "Fornari patent") at column 1, line 45 through column 2, line 39.
Great Britain Pat. No. 18,325 (hereinafter referred to as the "Bond patent") discloses an infuser device (the "Bond device") of the type that can be used to produce a hydrostatic pressure. The Bond device holds the solid material to be infused and can be raised and lowered in a liquid. The raising of the Bond device partially out of the liquid causes hydrostatic pressure forces to develop. The hydrostatic forces cause a high flow rate. However, the Bond device causes compaction of ground coffee beans contained within the device due to its longitudinally uniform cross section.
The device described in the Fornari patent (the "Fornari device") prevents compaction of ground coffee beans because the sachet which contains the ground coffee changes shape as it is raised and lowered within a container of water. However, the Fornari device cannot develop hydrostatic pressure, and consequently a high flow rate, because the sachet is constructed totally of a permeable material.
U.S. Pat. No. 2,123,054 (hereinafter referred to as the "Lamb et al. patent") discloses a device for making coffee (the "Lamb et al. device") that cannot develop hydrostatic pressure and, consequently, a high flow rate. The bag containing the coffee is formed of an inner sheet of filtering material and an outer semirigid perforated sheet, the latter mechanically reinforcing and supporting the inner sheet. Thus, the Lamb et al. device provides too many flow paths when the device is dunked that do not pass through the substance contained within the device.
U.S. Pat. No. 3,083,101 (hereinafter referred to as the "Noury patent") discloses a device (the "Noury device") for making coffee. The Noury device is an infuser which can be used in simple gravity coffee pots or coffee percolators working under the principles mentioned above. The Noury device, based on its construction, may prevent compaction but cannot develop hydrostatic pressure or a high liquid flow rate.
Great Britain Pat. No. 1,601,335 (hereinafter referred to as the "Ruskin patent") discloses a device (the "Ruskin device") for preparing beverages. The Ruskin device cannot develop hydrostatic pressure and causes compaction. The Ruskin device is an elongated stirrer with a perforated membrane affixed to one end that defines a container for the solid. The membrane permits liquid flow into the container. Infusion is facilitated by stirring the device in water. The stirring action causes wter to pass through the perforated membrane. However, the water tends to flow over, rather than through, the ground coffee. Hence, the water does not move the coffee grounds, and they tend to settle at the bottom, and compaction occurs.
U.S. Pat. No. 4,443,481 (hereinafter referred to as the "Donarumma et al. patent") discloses a coffee infuser (the "Donarumma et al. device"). The Donarumma et al. device has a handle for dunking, but cannot develop hydrostatic pressure because it is constructed of porous tea paper. Fluid flow through the Doaarumma et al. device will follow a path of least resistance, and, thus, will tend to flow around, rather than through, the coffee and through the exposed porous paper. Thus, dunking of the Donarumma et al. device may, in fact, enhance compaction.
U.S. Pat. No. 4,465,697 (hereinafter referred to as the "Brice et al. patent") discloses a coffee brewing apparatus (the "Brice et al. device"). The Brice et al. device contains baffles with or without perforations. The baffles form a plurality of at least partially closed compartments to retain the coffee. The gases generated during brewing flow through and around the baffles and vent through the handle of the device. Because of its design, hydrostatic pressure clearly cannot be developed within the Brice et al. device. While the baffles allow gases generated during brewing to pass in and around the ground coffee beans, compaction will occur within the partially closed compartments because the baffles act as collectors for wet coffee grounds.
Therefore, there exists a need for a device that can, in the brewing of a beverage, develop hydrostatic pressure, resulting in a high flow rate of liquid through the device, and at the same time, prevent compaction of the material to be infused, to ensure that liquid flow occurs through the material.